Manufacture of sugar



United States Patent 3,401,059 MANUFACTURE OF SUGAR John A. Casey,Pepper Pike, Ohio (2804 Brainard Road, Cleveland, Ohio 44124) NoDrawing. Filed Jan. 22, 1965, Ser. No. 427,513 Claims. (Cl. 127--61)ABSTRACT OF THE DISCLOSURE A solution of dioctyl sodium sulfo-succinateis added to the sugar juice, for example, to the vacuum pans during theboiling of the massecuite to reduce the boiling time and improve thecrystallization of the sugar and the separation of the molasses from thesugar.

This invention relates to the manufacture of sugar and more particularlyto improvements in the crystallization of sugar from sugar-containingsolutions as carried out in sugar mills and refineries. The invention isdescribed herein as applied to the production of cane sugar, but it isto be understood that it may also be used in the production of otherkinds of sugar, such as beet sugar.

In a typical sugar mill, the juice is first extracted from the cane,lime is added to control the pH, the juice is heated, and then it goesto a clarifier in which the precipitates formed by the action of heatand lime are eliminated to as great a degree as possible. The clarifiedjuice then travels to a series of evaporators or a multiple effectevaporator where the juice is concentrated from an enteringconcentration of about or 16% of sugar to a syrup having a concentrationof about 65% sugar. The syrup from the evaporators then proceeds tovacuum pans where further evaporation is accomplished by boil ing thesyrup under reduced pressure. The syrup is evaporated in vacuum pansuntil it becomes a saturated or super-saturated solution of sugar. Thesyrup is then seeded to initiate crystal growth and when an evaporatorpan has become filled with a fairly dense mixture of crystals and syrupknown as massecuite, the contents of the pan, called a strike, isdischarged. The strike is normally cooled, with slow mixing, in acrystallizer to permit additional extraction of sugar from molasses tocrystals as the mass cools. The mass is then centrifuged to separate thesugar crystals from the molasses.

In most sugar factories, the three-boiling system is employed. The firstboiling of pure syrup yields what is known as A sugar and A molasses.The A molasses with a footing of sugar crystals and some syrup isreboiled to provide a second massecuite which in turn provides what iscalled a B strike that provides B sugar and B molasses. The operation isagain repeated with the B molasses and a footing of sugar crystals andsyrup. The strike is called a C strike and the crystallization operationthen produces C sugar and C molasses, which is the final or blackstrapmolasses. The amount of sucrose in the C molasses is a measure of theefficiency of the extraction process. The smaller the percentage ofsucrose in the C molasses, the more efiicient the process. Also, the

smaller the amount of C, or final molasses that is produced for a givenamount of sugar juice, the more efficient the process. Ordinarily, the Aand B sugars are sold, while the C sugar is used for seeding.

Various known steps are taken to improve the eificiency of the processand to extract as much of the sugar as possible from the molasses. Also,certain compounds have been added to the sugar syrup before thecrystallization of the sugar in an effort to improve the quality of thesugar and to increase the percentage of crystalline sugar obtained fromthe juice. See for example, US. Patent No. 2,871,148, issued Jan. 27,1959.

3,401,059 Patented Sept. 10, 1968 The general object of the presentinvention is to provide an improved method of crystallizing sugarwhereby the yield of sugar is increased, the quality of the sugar isimproved, the boiling time required in the evaporators is substantiallyreduced, and the operation of the centrifuges is improved as compared toconventional methods and materials presently in use in thecrystallization of sugar. Another object is the provision of acomposition of matter suitable for use in carrying out this process.

According to the present invention, the foregoing ad vantages areobtained at reasonable cost by adding to the sugar juice, syrup ormassecuites a very small amount of a water soluble salt of asulfo-succinate ester wherein the ester groups are water insoluble, suchas dioctyl, dihexyl, di-isobutyl or ditridexyl. Sodium, potassium orammoni um salts may be used, the sodium salt being preferred from thestandpoints of cost, availability and effectiveness. The preferredcompound is dioctyl sodium sulfosuccinate. However, dihexyl, di-isobutyland di-tridecyl sulfo-succinates may also be used, although withslightly less improvement than is obtained with dioctyl sodiumsulfo-succinate. The material may be added to the vacuurn pans, to thecrystallizers or to the evaporators before the vacuum pans. It may beadded to the juice at an earlier stage but it should not be added at astage where lime is present to an extent sufficient to react with thematerial to produce a relatively insoluble calcium salt. Preferably, thematerial is added to the pans during boiling of the massecuites,although it may also be added advantageously to the crystallizer as thestrike is discharged to the crystallizer.

The amount added depends largely upon the concentration of sugar at thepoint of the process at which the material is added. Preferably, thematerial is added at a rate of from to part by weight of dioctyl sodiumsulfo-succinate per million parts of juice, syrup or massecuite, per 1percentage point of sucrose in the juice, syrup or massecuite by weight.For example, in juice containing 15% sucrose, 1.5 to 7.5 ppm. of dioctylsodium sulfo-succinate are added. In massecuite containing sucrose, 8 to40 ppm. of dioctyl sodium sulfo-succinate are added. The amount ofmaterial added is not critical so long as enough is added to obtain thedesired results. Amounts above the upper limits given do notsubstantially improve the results as compared to amounts within therange set forth and it is therefore uneconomical to exceed the upperlimits. When amounts below the lower limits are employed, optimumresults ordinarily cannot be obtained. The amount selected within theranges given depends upon the quality of the syrup, high quality,wellclarified syrup requiring less of the material for optimum resultsthan syrup that contains more impurities. From the standpoint of cost,it is desirable to avoid use of excess amounts of the material, but thisis not a factor of great moment since the benefits accruing from the useof the process are in most instances worth several times the cost of thematerial, even when amounts of material in the upper part of thepreferred range are employed.

Preferably, the material is added in the form of a solution consistingof 50% by weight of dioctyl sodium sulfosuccinate, 25% by weight ethylalcohol and 25 by weight water, or 50% by weight dioctyl sodiumsulfo-succinate, 25% by weight propylene glycol and 25% by weight water.Each of these is a free-flowing solution that can be added to the syrupwith little difficulty and that rapidly disperses in the syrup. Dioctylsodium sulfo-succinate in undiluted form is a waxy solid that would bediificult to handle and disperse in the syrup without special equipment,and in addition, tests have shown that the presence of a small amount ofethyl alcohol or propylene glycol, or both, in the syrup results in animprovement in the process as compared to the use of dioctyl sodium 3sulfo-succinate alone, probably because of dispersion of the dioctylsodium sulfo-succinate in the syrup. The amounts of water, ethyl alcoholand/ or propylene glycol can be varied substantially from those givenabove, and a that the sugar crystals are of improved quality, and thatthey are drier and whiter when they leave the centrifuge. Observationalso shows that the boiling in the pan is more uniform and more easilycontrolled, and that the molasses is less viscous and easier to handle.

mixture of ethyl alcohol and propylene glycol can be used 1f deslred.However, I prefer that the weight of ethyl As noted above, foregoingresults were obtained with alcohol, propylene glycol or mixture of thetwo be about the preferred solution consisting of 50% dioctyl sodium /2the weight of the dioctyl sodium sulfo-succinate pressulfo-succinate,25% water and 25% ethyl alcohol. Preent 1n the solution. liminary testswith propylene glycol in place of ethyl alco- The following tableindicates the nature of improve- 1101 indicate even greater improvement.Tests without the ment obtained in tests conducted in five sugarfactories. ethyl alcohol show slightly less improvement than the Tetsidentified by the same letter were made in the same tests given above,but the results are nevertheless remarkfactory, and in each factory thetests with the treatment able. I have not tested the other soluble saltsof sulfoaccordlng to the present invention immediately followedsuccinates listed above in sugar factories, but laboratory the testswithout the treatment so as to minimize possible tests with sucrosesolutions indicate that these materials effects of other variables. Alltests involved C sugars. The are also eifective in reducing viscosityand surface tension, additive, when used, consisted of by weight dioctylalthough not to as great a degree as the preferred dioctyl sodiumsulfo-succinate, 25% by weight water and 25% sodium sulfo-succinate. byweight ethyl alcohol. The amounts given are parts per The invention isalso useful in the refining of sugar in m1ll1on by weight of dioctylsodium sulfo-succinate in 20 sugar refineries where sugar from thefactories is disthe massecuites; the parts per million of the solutionwere solved and then recrystallized to purify it, and as noted doublethe amounts given in the table. above, in the production of othersugars, such as beet Average Apparent Approx. No. of boiling Percentpurity of percent Additive strikes time per decrease final in low TestNo. (p.p.m.) in test strike in boiling molasses grade (minutes) time(percent sugar sucrose) recovered (percent) 6 134 12 116 4 9e 13 213 e165 11 No data 9 No data 10 No data 10 No data From the foregoing, itwill be seen that in factory A, the boiling time was reduced 35.3%; infactory B, the reduction of boiling time was 17.5%; and in factory C,the boiling time was reduced 22.6%. This reduction in boiling timegives, in effect, a corresponding increase in the productive capacity ofthe pans without requiring any increased capital investment.Furthermore, the reduction in boiling time reduces fuel costs, andreduces the degradation of sucrose that takes place continually at lowrates due to elevated temperatures in the pans. The boiling timeapparently is reduced by reason of the reduced viscosity and reducedsurface tension of the syrup. The reduced viscosity evidently increasesthe rate of circulation of the syrup within the pan, eliminates localhot spots in the pan and possible degradation of the sugar crystalsbecause of hot spots, and also makes it possible to charge a given panwith a greater amount of syrup.

The reduced viscosity also improves the crystallization and facilitatesthe separation of the molasses from the sugar crystals in thecentrifuges. This is evidenced by the foregoing tests which show areduction in the percentage of sucrose contained in the molasses, thusindicating a corresponding increase in the percentage of sugar crystalsobtained from the juice. As the table shows, in the four factories wheredata on this point were obtained, the improvement ranged from 1.3% to3.7%.

The reduction in boiling and the general improvement in the boilingoperation resulting from the use of the present invention reduce theamount of degradation of the sucrose that takes place in the pans ascompared to prior practice, and this reduces the amount of finalmolasses that is produced for a given quantity of sugar juice, thusfurther increasing the yield. Quantitative data relating to this factorare not available at the present time, however.

In addition to directly measurable improvements, the improvementobtained by the process of the present invention is readily apparent tothe sugar boiler. From observation of the process and of the massecuitesat various stages of the process, the boiler immediately recognizessugar, facilitating the concentration of the sugar syrup in the pans,the crystallization of the sugar and the separation of the crystals fromthe molasses.

I claim:

1. A process of crystallizing sugar from a sugar-containing solutionwhich includes the step of adding to the sugar-containing solution awater soluble salt of a sulfosuccinate ester wherein the ester groupsare insoluble.

2. A process according to claim 1 wherein the salt is a material fromthe group consisting of dioctyl sodium sulfo-succinate,

dioctyl potassium sulfo-succinate,

dioctyl ammonium sulfo-succinate,

di-isobutyl sodium sulfo-succinate,

di-isobutyl potassium sulfo-succinate,

di-isobutyl ammonium sulfo-succinate,

dihexyl sodium sulfo'succinate,

dihexyl potassium sulfo-succinate,

dihexyl ammonium sulfo-succinate,

di-tridecyl sodium sulfo-succinate,

di-tridecyl potassium sulfo-succinate,

di-tridecyl ammonium sulfo-succinate.

3. A process according to claim I wherein a material from the groupconsisting of ethyl alcohol and propylene glycol is added to thesugar-containing solution along with the said salt.

4. In the process of crystallizing sugar, the step which comprisescarrying out the crystallization in the presence of dioctyl sodiumsulfo-succinate.

5. A process according to claim 4 wherein the dioctyl sodiumsulfo-succinate is present in the amount of from about to /2 part byweight of dioctyl sodium sulfosuccinate per million parts by weight ofthe material from which the sugar is crystallized per 1 percentage pointby weight of sucrose in said material.

6. In a process of crystallizing sugar from a sugar-containing solutionin which the sugar-containing solution is concentrated in an evaporator,further concentrated in a vacuum pan, crystallized in a crystallizer andthen centrifuged to separate the sugar crystals from the remainder ofthe solution, the improvement which includes the step of adding dioctylsodium sulfo-succinate to the sugarcontaining solution in the amount ofabout to /2 part by Weight of dioctyl sodium sulfo-succinate per millionparts by weight of solution per 1 percentage point of sucrose by Weightin the solution.

7. A process according to claim 6 wherein the dioctyl sodiumsulfo-succinate is added to the solution before it reache theevaporators.

8. A process according to claim 6 wherein the dioctyl sodiumsulfo-succinate is added to the solution in the evaporator.

9. A process according to claim 6 wherein the dioctyl sodiumsulfo-succinate is added to the solution in the vacuum pan.

10. A process according to claim 6 wherein the dioctyl sodiumsulfo-succinate is added to the solution as it is discharged to thecrystallizer.

References Cited UNITED STATES PATENTS 2,871,148 1/1959 Kent 127-582,591,704 4/1952 King 12758 FOREIGN PATENTS 760,121 10/1956 GreatBritain.

OTHER REFERENCES Moritsugu, T., Effect of Pan-Aid etc., item 418 on p.102 of Sugar Industry Abstracts, published by Tate & Lyle, Ltd., vol.28, No. 6, June 1966.

MORRIS O. WOLK, Primary Examiner.

D. G. CONLIN, Assistant Examiner.

